Lesson 6 - Growth and Yield

Question 1

what is growth and yield, describe each one

Answer 1

body of information and techniques concerned with estimating future conditions for forest stands

growth: the change in some characteristic (attribute) of a tree or stand over time
yield: the quantity of some attribute of a tree or stand that is present at some point in time

Question 2

explain MAI, CAI and PAI

Answer 2

mean annual increment: average growth of a tree or stand (yield at some age/age)

current annual increment: yearly growth, the difference in yield of two consecutive years

periodic annual increment: the average growth rate calculated over a specified time rate

Question 3

how do CAI and MAI interact

Answer 3

yield curve is sigmoidal, characterized by three growth stages
youth characterized by a steady increase in both the CAI and MAI
maturity characterized by a slowing of the CAI coupled with an increasing MAI
senescence characterized by decreasing CAI and MAI

Question 4

what is the culimination age

Answer 4

the age at which MAI is maximized

- stands managed with this as the rotation age, wood fibre is maximized

Question 5

How do we use growth and yield information

Answer 5

1. determining aac
2. updating inventories
3. choice of silviculture treatment
4. returns on investments
5. choosing rotation age
6. long term planning
7. comparison of production

Question 6

What are the factors that affect the growth of trees

Answer 6

species, site quality, density, insects/diseases/damaging agents, managerial inputs

Question 7

TSP vs PSP and what are they used for

Answer 7

temporary sample plot - measure the yield of stands, measured once
permanent sample plot - measure growth, revisited on many occasions

Question 8

What are yield tables and what are the different types

Answer 8

display stand conditions at various ages in tabular format

normal yield tables: based on data from fully stocked stand
empirical yield tables: based on data from stands with average stocking
variable density yield tables: incorporate some measure of stand density
managed stand yield tables: predict growth in stands that have been silviculturally treated in some fashion

Question 9

How can CAI be approximated

Answer 9

CAI = dbh x HT x W

W = width in metres of the last annual ring

Question 10

how can MAI be approximated

Answer 10

MAI = (dhb2 x HT)/(4 x age)

Question 11

What are some indicators of density

Answer 11

stems per ha, basal area per ha, average crown closure

Question 12

how do you determine site quality

Answer 12

direct measures:

• estimation from historical yield records
• estimation based on stand volume data
• estimation based on stand height data

indirect measures:

• estimation from overstory species relationships
• estimation from lesser vegetation characteristics
• estimation from topographic, climatic, and edaphic factors

Question 13

what is site index

Answer 13

an indicator of site quality, defined as the average height of a specified portion of the stand at some reference age

Question 14

what assumptions underlie the use of site index

Answer 14

1. the height of specific trees (usually dominants) is an indicator of site potential. the height of such trees is not influenced by non-site factors such as density and sire preparation
2. site index is constant over time
3. directions for calculating site index have been followed correctly in the field

Question 15

When to use site index

Answer 15

1. the species of interest must be present in the stand in sufficient numbers
2. the stand must be within a specified age range
3. the stand should be even-aged